You can kind of see the gears in the window on the first one, the second has them exposed which causes need for readjustment often. The gears turn when you turn their knob on both.
The gears on this necklace turn.
The way I do it it getting a stable base like this wood or a stiff filigree and I use brass machine screws, washers, very small tube pieces and nuts to mount the gears in such a way that they will interlock and turn each other. It takes a while and the more gears you use, the harder it is to keep them aligned and plaing nice with each other. It is possible though!